Interlocked switch actuators



July 17, 1956 w, D ET AL 2,755,354

INTERLOCKED SWITCH ACTUATORS Filed March 16. 1953 3 Sheets-Sheet I5 Y INENTORS Man i M filo/"neg United States Patent INTERLUCKED SWITCH ACTUATORS Wiliiam F. Dehn, Wauwatosa, and Lynn H. Matthias, Fox Point, Wis, assignors to Mien-Bradley (Iompany, Milwaukee, Win, a corporation of Wisconsin Application March 16, 1953, Serial No. 348,974

6 Claims. (Ci. 20098) This invention relates to mechanically interlocked electro-magnetically actuated electrical switches and it more specifically resides in a pair of electro-magnetic actuator and switch assemblies each having a contact actuating member associated with a mounting for a set of movable contacts disposed to be moved toward and away from a position of engagement with a set of stationary contacts, the movable contact actuating members being arranged on opposite sides of a central hindering bridge across and beneath which extends a link member cooperatively engaged at its ends and held loosely captive by the movable contact actuating members so as to be carried thereby toward and away from the bridge as the actuating members move toward and away from contact closing position, the hindering bridge being at a level permitting closure of a single actuator but blocking full movement of both of said contact actuating members to closed contact position; the pair of switches sometimes including a set of reversible auxiliary contacts detachably mounted on the central member with a contact operating finger extended into cooperative engagement with a movable contact actuating member to be moved toward and away from closed position, whereby the auxiliary contact may be selectively mounted as a normally open contact or as a normally closed contact.

So-called interlocked switches are used primarily for starting and reversing motors and are usually electromagneticaliy operated. They perform the functions of an electrically actuated remotely controllable doublethrow switch. It is essential to provide an interlock with in such switches which precludes simultaneous closure of forward and reverse contacts to ensure against short circuiting which would otherwise occur.

it is desirable also that interlocking means provided for this purpose closely follow switch movements, without contributing materially to the inertia of the moving parts so that switch action will not be detrimentally affected. It is, furthermore, desirable that the interlock be rugged so that it may continue proper functioning while withstanding heavy service requirements without the necessity of frequent inspection. Further, the effect of Wear in such an interlock should be such that the same will not cause a loss of positive interlock or the development of sluggish action. It is desirable also that such switches be as simple and compact as possible for a given rating.

it is an object of this invention to provide in a pair of interlocked switch actuators an interlock cooperatively engaged with each actuator that has a positive operation prohibiting movement of the second switch actuator to closure upon movement of the first actuator to contact closed position.

it is another object of this invention to provide an interlock for a pair of switch actuators that is of rugged construction and subject to a minimum of wear, so that heavy duty will not cause dimensional changes that would impair operation.

it is another object of this invention to provide an interice lock that has a negligible inertia factor and will not impede normal switch action.

It is also an object of this invention to provide a pair of electro-magnetically actuated interlocked switches with a common magnet frame for the two actuator magnets to permit greater compactness of the apparatus.

it is another object of this invention to provide auxiliary contacts for a pair of interlocked switch actuators in the form of a unit which may be installed as a normally open or as a normally closed contact.

These and other objects and advantages of this invention will appear in the description to follow. In the description, reference is made to the accompanying drawings, forming a part hereof, in which there is shown by way of illustration and not of limitation a specific form in which this invention may be embodied.

in the drawings:

Fig. l is a front view in elevation with parts broken away and in section of an interlocked reversing switch embodying this invention,

Fig. 2 is a fragmentary front view in elevation with parts broken away and in section of a portionof the switch shown in 1 showing the interlock between the actuators,

Fig. 3 is a side view in elevation partially in section of the switch viewed through the plane 3-3 indicated in Fig. i,

Fig. 4 is a bottom view in section of the switch viewed through the plane indicated in Fig. 1.

Fi 5 is a fragmentary side view in elevation in section of a portion of the switch shown in Fig. 3 showing the auxiliary contacts so mounted as to be in closed position while the main contacts of the switch are in closed position,

Fig. 6 is a fragmentary side view in elevation and in section of a portion of the switch shown in Fig. 3 showing the auxiliary contacts so mounted as to be in closed position while the main contacts of the switch are in open position, and

Pig. 7 is a side view in elevation of the auxiliary contact block and the mounting means therefore.

Referring now to the drawings, there is shown in Fig. l a reversing switch comprising a pair of electro-magnetic actuators and switch assemblies 1 and 2 that have a common magnet frame 3. The frame 3 is of stamped sheet steel formed to provide a vertical back wall 4 having upper mounting brackets 5 and lower mounting brackets 6 with openings to pass mu ing screws for securing the apparatus to a panel or the A top plate 7 is bent forwardly from the upper margin of the back wall 4 and to complete the frame 3 a separate forwardly extending bottom plate 3 is secured to the lower margin of the back wall 4 by machine screws 9.

The top plate 7 has fastened therein a pair of fixed circular steel pole pieces 10 that each have a central opening passing an associated non-ma netic armature plunger 11. Each armature plunger 11 carries a magnetic armature 32 disposed beneath the associated pole piece 10 for movement upwardh. toward downwardly from engagement with the pole piece in. The plungers 1i and their armatures 12 are in threaded engagement for movement as a unit, and lock nuts 13 threadedly received upon the lower end of the plungers it are brought up tight against the armatures 12 to secure the same.

The upper end of each armature 12 forms a pole face 14 for engagement with the associated fixed pole piece 10 and embedded in each pole face 14 is a shading coil 15. Each armature i2 is tapered near its bottom and extends through a secondary air gap opening 16 in the bottom plate 8.

A pair of coils 17 disposed between the top plate 7 and the bottom plate 8 of the magnet frame 3 each surround one of the fixed pole pieces and armature 12. Fiber end washers 18 are placed in customary manner at the top and bottom ends of each coil 17 and a pair of molded spacers 1% that rest upon the bottom plate 8 fit within the lower entrances of the coils 17 to position the coils 17 and also to form bearing guides for the lower ends of the armatures 12. Each spacer 12 has a plurality of downwardly extending positioning toes 2%) received within complementary openings in the bottom plate 8. Annular spring washers 21 resting on the spacers 1E urge each coil 17 upwardly against the underside of the top plate 7.

The upper end of each armature plunger 11 extends above the top plate 7 and is embedded within a molded movable contact cross bar 22 that rests upon the upper face of the top plate 7, which acts to limit downward travel of the armature assembly, when the associated coil is deenergized. Each cross bar 22 extends from the front to the back of the apparatus, and serves to mount three upwardly facing double bridging contacts 23 disposed in a row extending from the front to the back of the switch. Each contact 23 is free to move vertically with respect to its cross bar 22 and contact springs 24 are disposed beneath the contacts 23 to provide contact pressure. A pair of spaced guide shoulders 25 extend horizontally from each movable contact cross bar 22, toward the center for engagement with slide surfaces 37 to be described more fully hereinafter. Above each notch 26 is an auxiliary contact engaging ledge 27.

A vertical partition 28 disposed between the contact cross bars 22 and secured to the top plate 7 by a pair of mounting bolts 29 separates the sets of bridging contacts 23. A downwardly facing notch St in the partition 23, in alignment with the laterally facing notches 26 in the cross bars 22, extends upwardly from the top plate 7 to a hindering bridge 31, which furnishes a fulcrum, as shown in Fig. 2. An interlock bar 32 of thin flat rectangular configuration with slightly rounded ends extends through the notch 39 beneath the hindering bridge 31 and is held captive loosely in notches 26 formed in the facing sides of the cross bars 22.

A contact hood 33 formed integrally with the vertical partition 28 extends sidewardly to the left and right from the upper margin of the partition 28 and overhangs each of the movable contact cross bars 22. Terminals 34 mounted in the hood 33 project upwardly and carry terminal screws 47 for the convenient connection of electrical conductors. The lower extensions of the terminals 34 emerge beneath the hood 33 where stationary contacts 35 are secured thereto in facing relation to the bridging contacts 23. Contacts 35 are arranged in pairs so that each bridging contact 23 may engage one of said pairs upon moving into closed position. Partition ribs 36 on the underside of the hood 33 separate the pairs of contacts 35 and provide slide surfaces 37 in sliding engagement with the guide shoulders 25 of the cross bars 22.

Secured to the front face of the partition 28 by a mounting screw 39 is an auxiliary contact block 38 carrying terminals 52. The mounting screw 39 passes through the block 38 and into a channel 40 in the partition 23 where it engages a self securing spring nut 41 as shown in Fig. 4. The terminals 42 extend through the block 38 to provide support for stationary contacts 43. A second set of terminals 44 mounted in the block 38 each extends therethrough to provide support for flexible contact fingers 45 that carry movable contacts 46 disposed in facing relation to the stationary contacts 43. The flexible contact fingers 45 extend rearwardly beyond the movable contacts 46 to pass between the lower faces of auxiliary contact engaging ledges 27 and the upper face of the interlock bar 32.

Upon energization of one of the coils 17, for example coil 17 of switch 2, the upward movement of the as sociated armature 12 carries the respective cross bar 22 upwardly to close its bridging contacts 23 with stationary contacts 35. The guides 25 extending from the cross bars 22 sliding against the slide surfaces 37 prohibit rotation of the armature, thus retaining the bridging contacts 23 in alignment with the stationary contacts 35. The interlock bar 32 is carried with the cross bar 22 from a horizontal position well beneath the hindering bridge 31 upwardly into an oblique position, as shown in Fig. 2. The bar 32 in this position is disposed very close to, but out of contact with, the hindering bridge 31. if the second coil 17, of the switch 1, should now be energized as well, armature movement would attempt to carry the interlock bar 32 into immediate contact with the hindering bridge 31, thus blocking further upward travel of the armature 12 and its contact cross bar 22. Simultaneous closure of the contacts of both switches 1 and 2 is therefore precluded.

The interlock provided further ensures that upon deenergization of one switch and immediate energization of the other, the first must drop out of contact engagement before the second may close its contacts.

The common magnet frame 3 permits close spacing of the coils 17. Compactness is further enhanced by disposing the contacts in parallel rows to avoid overhanging be yond the sides of the coils. With the movable contact cross bars 22 also closely spaced the interlock bar 32 may be short and strong but with a correspondingly low moment of inertia.

The interlock bar 32 thus imposes negligible mechanical hindrance to proper movements of the switch armatures. The small dimensions and elimination of a plurality of pivotally joined members facilitate quick positive response. Engagement of the bar 32 with the hindering bridge 31 occurs only upon abnormal dual energization of the coils 17, thus there is little wear to cause dimensional change in the interlock of this invention.

The auxiliary contact block 33 may be mounted in either of two alternative positions. in the first position, shown in Figs. 3 and 5, the movable contact -36 is beneath the stationary contact 43 and the finger 45 is moved upward with the bar 32 upon energization of the associated switch to close the contacts 43, 46. In the second position, shown in Fig. 6, the block 38 is inverted with the finger 45 above the stationary contact 43. Deenergized position of the associated switch then causes the associated ledge 27 to move the auxiliary contacts 43, 45 to a normally closed position.

We claim:

1. In a pair of mechanically interlocked switches the combination comprising a pair of spaced movable actuators independently displaceable in substantially parallel paths between positions of rest and positions of actuation, a stiff non-defiectable interlock link extending between said actuators with the ends thereof having attachment with said actuators for joint movement at all times between each actuator and the link end with which it is attached wherein the attachment between the actuators and link ends provides the sole support for said link, and a stationary hindering bridge disposed between the ends of said link that extends along a minor length of the link in a position toward which said link is advanced upon actuation of an actuator to limit the movement of the minor length of the link to preclude simultaneous movement of said actuators to actuated positions.

2. In a pair of mechanically interlocked switches the combination comprising a pair of spaced movable actuators independently displaceable in substantially parallel paths between positions of rest and positions of actuation, each of said actuators having a recessed bearing seat disposed in facing relation to one another, a stiff nondeflectable interlock link extending lengthwise between said actuators having opposite ends extending within said bearing seats for the sole support thereof and held loosely captive in said bearing seats to require a joint movement Of both an end of said link and the associated actuator,

and a stationary hindering bridge disposed between the ends of said link across a medial portion of the length of the link in a position toward which said link is advanced upon actuation of one of said actuators to limit the movement of the medial portion of the link to preclude sin-ruitaneous movement of the ends of the link to positions corresponding to said positions of actuation of said actuatorsl 3. In a pair of mechanically interlocked switches the combination comprising a pair of spaced movable actuators independently displaceable in substantially parallel paths of movement toward and away from positions of rest and positions of actuation, a set of movable contacts carried on each of said actuators with each set disposed in a row parallel to the row of contacts of the other set, a stiff non-deflectab1e interlock link extending between said actuators with the opposite ends thereof cooperatively engaging the actuators for the sole support thereof and to be moved thereby upon movement of said actuators, a stationary contact support including a central member extending between the rows of movable contacts to separate the same having an opening through which said interlock link extends with a side wall forming a hindering bridge disposed across the path of movement of said interlock link in a position toward which said link is advanced upon actuation of one of said actuators and blocking simultaneous movement of said actuators to actuated positions, and stationary contacts mounted on said stationary contact support in spaced relation to said movable contacts to be engaged therewith upon movement of the respective actuators into actuated position.

4. In a pair of mechanically interlocked switches the combination comprising a magnet frame of channel configuration with a central web and top and bottom flange plates substantially normal to the web extending in like direction from opposite margins of the web, a pair of coils mounted between the top and bottom plates of said frame with central openings extending normal to said plates, a pair of armatures each movable in a central opening of one of said coils completing a magnetic circuit through said frame for said coil, a pair of movable members' each mounted on one of said armatures and displaceable with said armature between energized and deenergized positions, an interlock link extending between said movable members with the ends thereof having attachment with said members for joint movement at all times between each movable member and the link end with which it is attached wherein the attachment between the movable members and link ends provides the sole support for said link, and a stationary hindering bridge disposed between the ends of said link that extends along a minor length of the link in a position toward which said link is advanced upon movement of an armature to limit the movement of the minor length of the link to preclude simultaneous movement of said armatures to energizen positions.

5. In a pair of mechanically interlocked switches the combination comprising a pair of spaced movable actuators independently displaceable in substantially parallel paths between positions of rest and positions of actuation, interlock link means extending between said actuators with the ends thereof having attachment with said actuators for joint movement at all times between each actuator and the link end with which it is attached wherein the attachment between the actuators and link ends provides the sole support for said link, a stationary hindering bridge disposed across the path of movement of said interlock link means in a position toward which said link means is advanced upon actuation of one of said actuators and blocking simultaneous movement of said actuators to actuated positions, and a contact support block adapted to be fixed with respect to said hindering bridge in either of two positions having a stationary contact and a resilient finger member mounting a movable contact in facing relation to said stationary contact cooperatively engaged with one of said actuators to be moved thereby to carry said movable Contact into and away from engagement with said stationary contact, whereby one position of said block causes said auxiliary contacts to be open when the associated actuator is in a position of rest and the other position of said block causes said auxiliary contacts to be closed when the associated actuator is in a position of rest.

6. In a pair of mechanically interlocked switches the combination comprising a pair of spaced movable actuators independently displaceable in substantially parallel paths of movement toward and away from positions of rest and positions of actuation, interlock link means extending between said actuators with the ends thereof having attachment with said actuators for joint movement at all times between each actuator and the link end with which it is attached wherein the attachment between the actuators and link ends provides the sole support for said link and the link ends are moved by said actuators between positions corresponding to the positions of rest and actuation of said actuators, a central member extending between the rows of movable contacts forming a stationary hindering bridge disposed across the path of movement of said interlock link means in a position toward which said link means is advanced upon actuation of one of said actuators and blocking simultaneous movement of the ends of said link means to positions corresponding to said positions of actuation of said actuators, a detachably mounted auxiliary contact block secured to said central member adapted to be attached in either of two respectively inverted positions, a stationary contact mounted on said block, and a resilient finger supporting a movable contact attached to said block and cooperatively engaged with one of said actuators to be moved into and away from contact engaging position by said actuator, whereby one position or" said block causes said auxiliary contacts to be open when said actuator is in position of rest and the inverted position of said block causes said auxiliary contacts to be closed when said actuator is in position of rest.

References Cited in the file of this patent UNITED STATES PATENTS 704,336 Ihlder iuly 8, 1902 845,731 Eskilsson Feb. 26, 1907 965,671 Whittingham July 26, 1910 1,186,561 Evans a- June 13, 1916 1,486,386 Laing Mar. 11, 1924 2,108,634 Wilms Feb. 15, 1938 2,396,972 Russell Mar. 19, 1946 FOREIGN PATENTS 563,911 Great Britain Sept. 5, 1944 

